Tadalista 20 mg is a popular medication used to treat erectile dysfunction (ED) in men. Its active ingredient, Tadalafil, belongs to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors. Tadalafil helps increase blood flow to the penis, enabling men to achieve and maintain a firm erection during sexual stimulation.  Tadalafil works by relaxing the smooth muscles in the blood vessels of the penis. This relaxation allows blood to flow in more easily when sexually stimulated, resulting in an erection.